The field of the present invention relates to aircraft cargo nets.
Aircraft cargo nets are used primarily to restrain cargo in aircraft after the cargo has been placed on an aircraft pallet. Today, virtually all aircraft cargo nets are made of rope fabricated into a large diamond- or square-patterned net structure. Initially, the nets were constructed entirely of woven webbing stitched together at the interstices to form the patterned net structure. Then, for reasons of cost and ease of manufacture, knotted rope replaced the stitched-together webbing as the material of choice for commercial aircraft cargo nets approximately twenty-five years ago. Since then, cargo nets comprising webbing have seen little, if any, commercial use as rope nets have been used almost exclusively.
In use, cargo nets are subjected to substantial wear and tear. The environment in which cargo nets are used creates extensive abrasion on the net structure. Cargo nets may be significantly damaged by exposure to extreme weather conditions, repeated attachment and removal from cargo pallets, dragging across tarmacs and floors, and being run into and over by machinery such as forklifts. As a result, the life span of a cargo net may be drastically reduced.
The purpose of the cargo net, of course, is to hold the cargo in place on the pallet not only during the loading and unloading process, but also during flight. Planes must maintain balance within certain limits to remain flight-worth, and if cargo nets failed during flight leading to a sufficiently large shifting of cargo and hence weight within the hold of an airplane, the plane""s ability to fly could be compromised. Indeed, there have been plane crashes there were attributed to shifting of cargo.
Therefore, cargo nets are frequently inspected, and if damaged or worn, must be repaired or replaced. That creates cost and delay, and is therefore to be avoided to the extent possible.
Not surprisingly, it is the lower rope section of the cargo net, which is that section nearest where the cargo net attaches to the pallet, that suffers the most abrasion and wear and tear. The abrasion and wear and tear on this section of the net has several sources, with pallet attachment fittings causing the bulk of the damage by continuously rubbing against the ropes they are attached to. When the cargo net is not attached to an aircraft pallet, the fittings may slide freely back and forth along the rope and cause minor abrasions. When a cargo net is attached to a pallet, the net is tightened about the pallet and its contents. Tightening the net creates a great deal of additional pressure between the fittings and the ropes. The additional pressure only exacerbates the abrasive effect the fittings have on the ropes, especially as the pallet is moved and jostled about during transportation. Thus, the fittings steadily deteriorate the condition of the ropes they are attached to until the cargo net becomes unusable. The rope, being round, tends to allow the fittings to move more easily along the rope, and tends to concentrate the abrasion from the fittings on one side of the rope, thereby hastening to extent of the damage.
Therefore, there is a need in the art for an improved air cargo net that exhibits increase resistance to the wear and tear to which the nets are routinely subjected.
The present invention is a cargo net in which the upper sections of the net, that is the portions that in normal use will reside on the top and upper sides of the cargo on the pallet, being constructed of conventional knotted rope, but with the lower section of the net constructed with webbing. The rope and webbing sections are preferrably joined together by knotting. Preferably, the webbing is flat on both sides. The flat sides of the webbing reduce the wear and tear on the lower section of the cargo net by spreading the abrasive forces over a larger surface area. Reducing wear and tear on the lower section of the cargo net increases the life span of the cargo net.
In the preferred embodiment of this invention, on the very lowest section of the net; that is, the section that is attached to the fittings, is comprised of webbing. Alternatively, a larger section of the cargo net or the entire cargo net could be comprised of knotted webbing.